1. Field of the Invention
The present invention relates to tolerance rings and more particularly to improvements in the use of tolerance rings to provide their use for mounting in relatively soft materials.
2. Description of the Prior Art
Tolerance rings are generally formed as split ring members having a corrugated or wavy surface and are sandwiched between two cylindrical surfaces, that is, an outer cylindrical surface and an inner cylindrical surface, to provide frictional engagement between two members having the respective cylindrical surfaces. The corrugations or waves on the ring may protrude inwardly from an outer surface thereof, outwardly from an inner surface thereof or alternatively inwardly and outwardly. Such tolerance rings are illustrated in U.S. Pat. Nos. 3,142,887 and 3,145,547. The corrugations on the tolerance rings may be of varying heights or may be arranged in more than one row around the circumference of the ring as illustrated in U.S. Pat. Nos. 3,700,271; 3,838,928 and 4,286,894.
In some applications it is desirable to mount a cylindrical member within a hole in a relatively soft material such as plastic or metal powder parts. Tolerance rings may be used to provide an increased frictional engagement between the cylindrical member and the hole in the soft material due to a compression of the corrugations of the ring, however, if there is a significant amount of vibration or radial load present, the tolerance ring may tend to deform the soft material or to set in the material such that the corrugations will no longer be compressed, thereby resulting in a loss of frictional engagement between the cylindrical member and the hole.
In other applications the tolerance ring may surround a cylindrical object formed of a relatively soft material and that assembly inserted into a hole whereby compression of the corrugations on the ring will provide a desired frictional engagement between the cylindrical object and the hole. Again if the two objects, the cylindrical member and the object in which the hole is located, are subject to vibration or radial loads, the tolerance ring may set into the soft cylindrical object thereby resulting in a loss of frictional engagement. Thus, it would be desirable to have a means for preventing such setting or deformation of the relatively soft material by the tolerance ring. Also, the force of the corrugations under their normal compression will sometimes deform the adjoining surface if it is a soft material, without requiring additional forces such as vibration or radial loading.